On Friday, the ACLU of Delaware filed a brief with the Delaware Supreme Court arguing that law enforcement agents should not be permitted to attach a GPS device to a car without getting a search warrant. The brief explains that because GPS tracking is an invasive form of surveillance capable of revealing many private facts about a person, a lower court was correct to conclude that, “absent exigent circumstances, the warrantless placement of a GPS device to track a suspect 24 hours a day constitutes an unlawful search.”

In the case, agents attached a battery-operated GPS device to Michael Holden’s car while it was parked on a public street. They did not obtain a warrant and left the device on his car for 19 days. It collected information about the vehicle’s location the whole time.